US Patent 11930875 Impact reduction system for personal protective devices

Personal protective devices with an impact reduction system that includes a first bladder system including a fluid and a second bladder system are disclosed. A passage couples the first bladder system to the second bladder system and includes a first series of Tesla valves that resist flow of the fluid from the first bladder system to a common point of the passageway when an impact occurs to the first bladder system. In some embodiments, the passage further includes a second series of Tesla valves that resist flow of the fluid from the second bladder system to the common point of the passageway when an impact occurs to the second bladder system. The impact reduction system is a passive, closed system.